Continuous drying and/or heating apparatus

ABSTRACT

This invention comprises an apparatus and process for drying and/or heating materials. This invention was designed for use in the production of charcoal from wood feed material; however, it can be used to heat and/or dry many types of materials. Feed material is disposed in a reactor, wherein there is provided a first array of input channels extending through said feed material, through which hot gases are introduced into said feed material, and a second array of output channels extending through said feed material to collect and exit those hot gases and any gases or vapors derived from the heating and/or drying of the feed material.

SUMMARY

This invention was primarily designed for the continuous production ofcharcoal from wood feed material. However, the invention has been foundto be useful in many other areas. While its primary use is still as acharcoal producing apparatus, it can also be used in grain drying, bulkpowder storage, various calcining processes, such as CaCO₃ →CaO and inmany other instances. The apparatus can be used any time it is desiredto dry or heat feed material such as powders, grains or chips. As theinvention was primarily designed to produce charcoal, its use as acharcoal producer will be described in detail.

The basic problem of charring wood chips, or sawdust, or any wood feedto produce charcoal, is to uniformly heat a significant mass of the feedmaterial in an oxygen deficient atmosphere while efficiently collectingand managing the evolved gases. The present invention allows for the hotgases heating the charcoal producing feed material, to be uniformlycirculated therethrough, and to be uniformly collected along with thegases and vapors produced by the charcoal producing reaction. Inaccordance with this invention, feed material is made into charcoal in ashort time, using little energy. The present invention also provides forefficient control and collection of the gases, preventing them fromescaping into the atmosphere, thereby eliminating pollution. Anadvantage of this invention is that some of the released and collectedgases and vapors are burned to provide energy to be used in the process;thus, the external energy needed for the process is reduced. Further,some of the collected hot gases are circulated in the charcoal producingprocess, thereby preserving energy.

The invention comprises a process and apparatus for the heating anddrying of materials in powder, chip, or grain form. For convenience anapparatus embodying the invention as used as a charcoal producer isdescribed below. However, this embodiment is but one way to carry outthe inventive process and is but one embodiment of the inventionapparatus. The apparatus comprises means for circulating hot gasesthrough woody feed material in a reactor which provides an oxygendeficient atmosphere; wherein said means include an array of inputchannels extending through the feed material, through which hot gasesare introduced into the feed material, and an interleaved array ofoutput channels extending through the feed material to collect, manage,and discharge said hot gases and any gases and vapors released by thecharcoal producing reaction.

It is an object of this invention to provide an apparatus and processfor the heating and/or drying of materials such as powders, grains, orchips.

It is also an object of this invention to provide an apparatus capableof using wood waste in the form of chips or sawdust without size sortingand to produce charcoal from them.

It is also an object of this invention to provide a charcoal producingapparatus small enough to be contained on a flat bed trailer forconvenient portability.

It is also an object of this invention to provide an apparatus for theproduction of charcoal which is amenable to simple automation forminimal operator attention and the reactor of which has no moving parts.

It is also an object of this invention to collect condensible vaporsfrom a charcoal producing reaction without the need for tight mechanicalseals, and to burn the generated non-condensible gases to return heatinto the reaction, while eliminating atmospheric pollution and reducingexternal energy requirements.

It is also an object of this invention to use heat from the charringprocess to dry the chips or sawdust feed material prior to theirinsertion into the charring process or apparatus.

How the foregoing and other objects are achieved are described in thedetailed description below and in the accompanying figures in which:

FIG. 1 is a schematic view of the apparatus;

FIG. 2 is a partial vertical sectional view of the apparatus of FIG. 1;

FIG. 3 is a sectional view taken along lines 3--3 of FIG. 2;

FIG. 4 is a fragmentary vertical sectional view of the filled reactor ofapparatus of FIG. 1;

FIG. 5 is a perspective view of a reactor module;

FIG. 6 is a side view of the conveyor of the apparatus of FIG. 1;

FIG. 7 is a sectional view of the conveyor taken along line 7--7 of FIG.6;

FIG. 8 is a sectional view of the conveyor taken along line 8--8 of FIG.6;

FIG. 9 is a side view of another reactor unit embodying invention;

FIG. 10 is a partial sectional view of the reactor of FIG. 9 taken alonglines 10--10 of FIG. 9;

FIG. 11 is a partial sectional view of the reactor of FIG. 9 taken alongline 11--11 of FIG. 9; and

FIG. 12 is a perspective view of a wall of the reactor of FIG. 9.

DETAILED DESCRIPTION

The present invention was originally designed as a charcoal producer.While numerous other uses have been found for it, its primary purpose isstill as a charcoal producer; thus, the detailed description willdescribe the apparatus in its charcoal producing function. Nolimitations as to the uses of the apparatus or process are intended. Inaddition, while the description is of the apparatus, the inventiveprocess is embodied in that apparatus, and the invention is not limitedto an apparatus.

Charcoal is produced by heating wood feed material in oxygen deficientatmosphere. In the apparatus and process for the continuous productionof charcoal there are essentially two systems involved; first, themovement of the hot gases, and second, the movement of the wood feedmaterial into and out of the apparatus.

The movement of the hot gas is shown schematically in the apparatus ofFIG. 1. Fuel gas enters heating system 14 through valve 32 and is burnedby upper burner 33 of the pair of burners 33 and 35. Its fumes rise andexit through chimney 47. Fan 19 blows air around cylinder 76 of heatingunit 14 where it is heated by the burning fuel gas and kept from mixingwith the fuel gas or its fumes. In this embodiment as it is convenient,air is used as the heat carrier; however, there are no limits as to thetype of gas to be heated and used as the carrier of heat, other thanthose imposed by the charring process itself. However, when air, meaningO₂ and N₂, is used only at start up of the apparatus, as the oxygen isconsumed the feed material 12 is heated up to reaction temperature.Thereafter, gases are recirculated and any excess gas is introduced toburner 35 described below. The hot recirculating gas exits cylinder 76through valve 15 and, during the producing stage of the apparatus, goesupwards through pipe 41, through input pipes 22,23,24, and 25, and intocharcoal reactor unit 11. Dampers 74 adjust the flow through pipes 22-25and manometers 73 measure the pressures at different levels within unit11. As will be shown, it is desired that the pressure at the top andbottom of reactor unit 11 be at atmospheric pressure to prevent escapeof polluting gases and dampers 74 and valve 75 are adjusted to achievethis.

The hot gases then circulate through the feed material 12 in reactorunit 11, as will be described below in greater detail. The hot gases andany gases produced by the charring process are collected and exitreactor unit 11 through output pipes 26,27,28,29 and 30. From there itgoes through escape pipe 46, through valve 31 and pipe 72, and intochamber 37 which is positioned along a length of conveyor 13. In chamber37 condensible vapors, in the hot gases supplied thereto, condense andmove into liquid traps 16,17 and 18. The hot gases then exit chamber 37through pipe 38, and go down chimney 47 via pipe 20 where they arepreheated by the fumes rising off burner 33. The hot recycled gases gothrough valve 34, into fan 19, and then, in part, go through valve 75 tobe burned in burner 35 and, in part, go through clyinder 76 to bereheated and recycled.

While the hot gas is being recirculated, feed material 12 moves asfollows. It is first placed on conveyor 13 and is carried up conveyor 13by screw auger 36 while being heated and dried by the hot gas in chamber37. The feed material 12 is then dropped through connection 39 into thetop 49 of reactor unit 11. Feed material 12 at the top 49 of reactorunit 11, slowly makes its way down through reactor while being heated bythe hot gas and made into charcoal. The charcoal is then removed fromthe bottom 50 of the reactor unit 11 by removal auger 48.

Feed material 12 moves down the reactor unit 11 due to the removal ofcharcoal by removal auger 48 and due to the continuous shrinkage of thefeed material 12 during the charring process. Therefore, the speed ofconveyor 13, of fan 19, and of removal auger 48 are set such that feedmaterial 12 is converted into charcoal by the time it reaches the bottom50. This permits the process and apparatus to be continuous as new feedmaterial is constantly being added at the top 49 of reactor unit 11,while charcoal is constantly removed from bottom 50 of reactor unit 11.Downward movement of the feed material 12 through the reactor unit 11 isassisted by the vibration imparted to reactor unit 11 by fan 19, loadauger 36, unload auger 48, and the machines driving them. Shouldplugging or clogging of the reactor 11 ever be a problem, the lodgedmaterial could be loosened by auxiliary mechanical jarring of thereactor unit 11. If such lodging becomes frequent, intermittent jarringis easily mechanized.

Reactor unit 11 has a wall 45 on its one side, and opposed alternatinglystacked input 51 and output 40 reactor modules. FIG. 5 shows a typicaloutput module 40. Output pipe 26 is connected to output module 40 whichhas angled members 44 connected to its core 42 at holes 43. The onlydifference between an input module 51 and an output module 40 is thenumber and position of the holes 43 and of the angled members 44 and 52.An input module 51 has five holes 43 and three full angled members 44and two half angled members 52, whereas an output module has four holes43 and four full angled members 44. (See FIG. 3).

FIG. 3 shows a more detailed picture of the alignment of modules 40 and51 and of their respective holes 43 and angled members 44 and 52. Feedpipe 41 is shown connected to input pipes 22-25 which are, in turn,connected to input modules. Escape pipe 46 is connected to output pipes26-30 which are in turn connected to output modules 40. The holes 43 ofinput reactor module 51 and output reactor module 40 are offset asshown. The ratio of holes 43 and their relative alignment is a merepreferred embodiment of the invention and is not required.

FIG. 4 shows the flow of gases. A portion of reactor unit 11 is shownfilled with feed material 12. Diamond shaped channels 53 are created infeed material 12, as it is deflected by angled pieces 44 and 52 (52 notshown in FIG. 4) while moving downward through reactor unit 11. Hotgases flow from feed pipe 41, through input pipe 22, into core 42 onthrough the five holes 43, and into channels 53 created by angledmembers 44 and 52. The hot gases then circulate through feed material 12and are collected by and exit through channels 53 created by angledmembers 44 of the output modules 40. These channels 53 provide largesurface areas for the hot gases to uniformly penetrate the feed material12. In addition the gases have short distances to travel preventingcondensation of the gas vapors in cool areas of the feed material 12.

Channels 53 extend through feed material 12 and are created by angledmembers 44 and 52 which push feed material 12 aside as it movesdownward. Any other means for producing such channels 53 is equallywithin the scope of this invention. Not only angled members 44 willcreate channels 53 within the scope of the invention, but also flatmembers, flat members with slightly curved edges, inverted U-shapedmembers, or even cylindrical members with apertures at their bottom. Inthis embodiment, the means for creating a channel also break up and stirthe feed around as it moves downward.

Channels 53 allow the introduction of the hot gases throughout theirentire length, which is substantially the entire width of reactor unit11. Thus, feed material 12 along the entire width of reactor unit 11 isuniformly heated by the hot gases. Without these channels 53, the hotgas would enter the reactor unit 11 at a point or series of points andchar the feed material 12 immediately surrounding the point or points.The hot gases would then go straight to an exit and only the feedmaterial 12 along that path would get heated and char. If it charred atall, the other feed material 12 would only char after a long time, aslittle heat would reach it. A large waste of energy would be created as,after being made into charcoal, feed material 12 near the input channelwould be heated until the heat reached feed material 12 far from theinput channels. In addition, a poor quality charcoal would be producedas the feed material 12 would not be uniformly charred.

In this, the preferred embodiment, there is a uniform array of channels53 across substantially the entire length of unit 11 (as can be seen inFIG. 2). In addition to creating a proper circulation of hot gases thesechannels cause the regular break up of feed material 12 moving downreactor unit 11 and allow different portions of feed material 12 to bein direct contact with the hot gases. The channels 53 also inhibitpacking or densification of material 12 in the reactor. Any localsettling merely alters the bottom V-angle of channel 53 withoutsignificantly compacting material 12. At no depth in the reactor doesthe feed material 12 "feel" the entire load of the column of materialabout it, rather, the array of angled members 44 and 52 share some ofthe load. Furthermore, more of the individual angled members 44 and 52bear a heavy load. The array of output channels 53 similarly allows forthe uniform collection of both the hot gas and any gases or vaporsproduced by the charring process; thus, preventing them from merelyescaping into the atmosphere and polluting it. Some of these gases canbe burned to provide energy, be used again in the charring process, orbe used to dry the feed material.

FIG. 6 shows feed material 12 being pushed up conveyor 13 by screw auger36 which is driven by a motor (unseen). FIG. 7 shows a cross section ofconveyor 13 at a point which does not contain chamber 37. U-shapedtrough 55 with its molding 56 is shown containing screw auger 36. FIG. 8shows a cross sectional view of conveyor 13 at a point containingchamber 37. U-shaped trough 55 and U-shaped container 57 have theirupper parts welded together at point 58. Between U-shaped trough 55 andU-shaped container 57 is chamber 37.

Referring back to FIG. 1 the start-up of the operation will be describedfrom the time at which reactor unit 11 is unfilled. To start theprocess, the liquid traps 16, 17 and 18 are filled to prevent the lossof hot air to the atmosphere. Burner 33 is then lit and set for maximumoutput, and fan 19 is started with its speed adjusted to keep outputtemperature at a desired level. Air is heated in cylinder 76 of heater14 and is pushed up through valve 15 which has been adjusted to divertthe hot air into pipe 71 through chamber 37 of conveyor 13, out pipe 38,down chimney 47, through pipe 20, and into heater 14 where it isreheated and recylced.

Feed material 12 is then added to conveyor auger 36 whose speed is setto ensure that the feed material 12 is dry when it reaches the top ofconveyor 13. When reactor unit 11 is filled with feed material 12, valve15 is switched to direct hot air into reactor module 11. The speed offan 19 is adjusted so that the air exits heat exchange cylinder 76 attemperatures typically ranging from 750° to 1000° F. In order to preheatthe feed material at the bottom of reactor unit 11, the dampers 74 areadjusted to allow hot air to enter the reactor unit 11 only throughinput pipes 24 and 25. The feed material 12 initially at the bottom ofunit 11 has less of a distance to move; thus it will be heated for amuch shorter time. Therefore, to ensure that it is fully charred whenremoved, it must be preheated.

As the feed material 12 is heated, the first evidence of a charringreaction is the evolution of vapors which condense in liquid traps 16,17 and 18. This causes a build up of gas pressure in the system which isreflected in U tube manometers 73. Dampers 74 are then adjusted to letthe hot gas go through all input pipes 22-25. The dampers 74 and valve75 are further adjusted to keep the pressures at top manometer 73 andbottom manometer 73 just at atmospheric pressure. Pressures at manometer73 on input modules will, of course, be above atmospheric pressure whilepressures within output modules will be below atmospheric pressure. Asthe reaction proceeds, a flame will develop in lower burner 35, burningthe combustible gases which have returned through valve 75.

During the start-up of the reaction, the accumulating gases beingreleased from the recirculating "closed" circuit through valve 75 willnot be combustible as they still consists of mostly water vapor, CO₂, O₂and only dilute amount of combustibles (CO, H₂, CH₃, etc.) which will beconsumed in the overhead gas flame of burner 33. However, as thereaction proceeds, the gases through valve 75 become more combustibleand a flame develops in lower burner 35.

The completion of the charring reaction in reactor unit 11 is evidencedby a reduced gas flow through valve 75. When this condition is achieved,the removal auger 48 is started, new feed material 12 is loaded ontoauger 36, and the machine operates as described above. During the steadystate operation, burners 33 and 35 are set to maintain a constant outputtemperature. The speed of feed auger 36 is set to add feed material 12to reactor unit 11 at a rate commensurate with the removal rate ofremoval auger 48.

While the apparatus can be continuously used to produce charcoal, it canalso be stopped. To stop the operation no new feed material is loadedonto auger 36 and removal auger 48 is stopped. Valve 31 is set so thatall gases which exit the reactor unit 11 through escape pipe 46 gothrough valve 31, down valve 34, through fan 19, and up through valve 69to burner 70, where they are burned off without producing new hot gas inthe apparatus. During this operation valve 32 and 75 are closed so thatrecirculating gas is not reheated. Valve 69 is adjusted to relieve anypressure build up of gases.

FIG. 9 shows another embodiment of the reactor module unit of thecharcoal producing apparatus. In this embodiment the heated gases enterthe reactor unit through feed pipe 59 (taking the place of pipe 41), gointo the chamber 81 of the reactor, through holes 63 in wall 66, andinto the chambers 53 created by inlet angled pieces 62. From there theair circulates through the feed material 12, goes into chambers 53created by the outlet angled pieces 61, through hole 64 on outlet wall67, into the chamber 82 and out through outlet pipe 60 (which takes theplace of pipe 46). As was discussed above, the pressures in the upperand lower parts of the reactor unit must be controllable; thus, baffles79 and 80 are located in chamber 82 and can be independently opened orclosed as they revolve on hinges 77 and 78. Thus, when the baffles 79and 80 are in the horizontal positions, the pressures in the top andbottom areas of the reactor unit are allowed to build. As the baffles 79and 80 rotate on hinges 77 and 78 into vertical positions, the gases areallowed to escape through outlet pipe 60 relieving the build up ofpressure.

FIG. 10 shows the inlet wall 66 with holes 63 inlet angled pieces 62 andoutlet angled pieces 61. FIG. 11 shows outlet wall 67 with outlet holes64 outlet angled pieces 64 and inlet angled pieces 62. As can be seen,the angled pieces in this embodiment range the whole width of thereactor unit, and are attached to the walls 66 and 67. In thisembodiment, there are triangular pieces 65 and U-shaped pieces 83 (shownbetter in FIG. 12) upon which the angled pieces 62 hang and into whichthe half-angled pieces 84 are placed. While the embodiment of FIG. 9 isobviously more suited for this method of attaching the angled pieces, itis clear that in the first embodiment discussed this method could alsobe used.

The present invention, with its array of input channels extendingthrough the feed material, allows for uniform charring of the feedmaterial. The hot gases are introduced through the channels, anduniformly reach and heat the feed material to make uniform qualitycharcoal. Without these channels, the feed material closest to theentering hot gases would be charred first. In the present invention, noenergy is wasted heating feed material that has already charred to allowhot gases to slowly make their way to feed material far from theentrance. The time necessary to char, and the energy required to charare, thereby, held to a minimum.

The array of output channels which extend through the feed material tocollect the hot gases, and through which the hot gases exit, allow foran efficient collection and management of the gases. That is, both thehot air and the gases and vapors produced by the charring reactionitself, are efficiently collected and managed instead of merely beingallowed to escape into the atmosphere to pollute. This efficientcollection of gases has many benefits, as the collected gases can beused in the condensor conveyor to dry and heat the feed material beforeit enters the reactor module, or can be used again in the charringreaction after being heated. This is a benefit as these gases arealready hot, and a minimum of energy is needed to bring theirtemperature up to that required by the charring reaction. In addition,any combustible gases (including those created by the charring), whichare efficiently collected, can be used in the lower burner 35, asdescribed. Thus, the amount of fuel gas necessary to continue thecharring reaction is reduced, or eliminated entirely after start up.

While the present invention has been described as an apparatus for theproduction of charcoal, it has many other uses. Among those uses aregrain drying, bulk powder storage and various calcining processes suchas CaCO₃ →CaO. As can be seen from the detailed description above, thepresent invention would be useful in those other applications. Thepresent invention circulates hot gases through a mass of feed materialand collects those gases efficiently. While some types of feed materialundergo a reaction (wood feed material and CaCO₃) other types of feedmaterial do not (grains and some powders). The apparatus or process isin no way dependent upon the feed material undergoing a reaction. Theinvention merely supplies the hot gases efficiently and efficientlycollects them. The present invention is excellent for the drying of anytype of material as the channels through the feed material regularlybreak up the feed material as it moves through the reactor unit. Thisregular breakup prevents the clumping of material, and allows differentsurface areas of the feed material to be exposed to the hot gases. Inaddition, it allows the hot gases to properly and efficiently circulateuniformally throughout the entire mass of feed material.

While the invention has been particularly shown and described withreference to a preferred embodiment of the apparatus and processthereof, it will be understood by those skilled in the art that variouschanges in form and details may be made therein without departing fromthe spirit and scope of the invention.

We claim:
 1. A reactor for the heating or drying of powders, grains,chips, and other feed materials comprising:a chamber for containing thefeed material to be heated or dried; inlet means at the top of saidchamber for depositing said feed material in said chamber; outlet meansat the bottom of said chamber for removing feed material which has beenheated or dried; a uniform array of input means vertically disposedwithin said chamber across substantially the entire length and extendinghorizontally across substantially the entire width of said chamber forintroducing hot gases therein, said uniform array of input meansextending through said feed material in direct contact therewith so thatsaid hot gases introduced into said chamber uniformly contact said feedmaterial; a uniform array of output means vertically disposed withinsaid chamber across substantially the entire length and extendinghorizontally across substantially the entire width of said chamber forwithdrawing said hot gases and any gases produced within said chamber,said uniform array of output means extending through said feed materialin direct contact therewith so that said hot gases and gases producedwithin said chamber may be uniformly collected; means for regulating theflow of said hot gases introduced into said chamber through said uniformarray of input means; means for pre-heating or drying said feed materialprior to depositing said feed material in said chamber; means forconducting said hot gases and said gases produced within said chamberaway from said chamber, said means for conducting being connected withsaid pre-heating or drying means so that heat derived from said hotgases and gases produced within said chamber is used to accomplishpre-heating or drying; means for regulating the flow of said hot gasesand gases produced within said chamber and withdrawn therefrom throughsaid uniform array of output means and conducted to said pre-heating anddrying means through said conducting means; and means for burningcombustible gases included within said hot gases and gases producedwithin said chamber, said means for burning communicating with saidpre-heating or drying means so that gases enter said means for burningafter passing through said pre-heating or drying means.
 2. The reactorof claim 1 wherein said uniform array of input means and said uniformarray of output means are alternating rows of inverted V-shaped members.